Sealing apparatus and method

ABSTRACT

A sealing apparatus ( 10 ) for use in establishing a seal in an annulus ( 12 ) between a mandrel ( 18 ) and a bore wall ( 14 ) has an annular seal element ( 20 ) initially activateable between a first, retracted, configuration and a second, expanded, configuration. The seal element ( 20 ) is disposed around a mandrel ( 18 ) and is free to move relative the mandrel ( 18 ) such that when the seal element ( 20 ) defines the second, expanded, configuration, pressurised fluid from the annulus ( 12 ) urges the seal element ( 20 ) into sealing or enhanced sealing engagement with the bore wall ( 14 ).

FIELD OF THE INVENTION

This invention relates to a sealing apparatus and method for use inestablishing a seal in an annulus between a mandrel and a bore wall.More particularly, but not exclusively, embodiments of the invention maytake the form of a downhole packer for use in sealing a wellboreannulus.

BACKGROUND TO THE INVENTION

Sealing apparatus and methods are used in many industries where it isdesired to isolate, seal off or otherwise control movement of fluid in agiven environment. In the oil and gas industry for example, sealingdevices known as packers are commonly used to seal the annulus between aproduction conduit or the like, and a bore wall or a surrounding casingor other tubular.

In some instances, one or more packer may be used to prevent undesiredmovement of fluid up or down the annulus in order to seal off thewellbore. In other instances, a number of packers may be used to createan isolated annular region which, amongst other things, permitsisolation of a problematic formation or permits controlled productionfrom, or access into, a selected region of a formation.

Known packers may comprise an elastomeric annular sealing elementmounted on a mandrel and which is capable of being extended radiallyoutwardly to engage, for example, the wall of a bore in which the packeris located, thus providing a seal in the annulus defined between themandrel and the bore wall. In some instances, the seal element may beaxially compressed, for example by a setting tool, to effect radialexpansion. In other instances, a swelling elastomer may be used which,in use, swells in response to the presence of an activation mediumpresent in the annulus.

While such packers are effective and may be used reliably in a number ofapplications, the high temperature and pressure differences experiencedin a downhole environment place particularly high demands on the sealelements of the packer to maintain the seal with the bore wall, thesuccessful maintenance of the seal often being of critical importance tothe safe, reliable and economic operation of the wellbore.

In view of the importance of maintaining the seal, packers are typicallydesigned to apply large forces sufficient to overcome and resist theforces expected during deployment and in use. In some instances,however, the pressure difference acting across the seal element may besufficient to cause extrusion of the seal element, thereby reducing sealperformance or making activation more difficult or in more extreme casesrisking failure of the seal. In other instances, the use of largeapplied activation forces may be prevented or restricted due to thepossibility of damaging the surrounding bore wall or tubulars.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda sealing apparatus for use in establishing a seal in an annulus betweena mandrel and a bore wall, the apparatus comprising:

a mandrel; and

a seal element disposed on the mandrel, the seal element configured todefine a first configuration and a second, expanded, configuration, theapparatus configured so that in the second configuration fluid from theannulus acts on the seal element to urge the seal element from thesecond configuration to a third configuration providing sealing orenhanced sealing engagement with the bore wall.

In use, the apparatus may be run into a bore with the seal elementdefining a first, retracted, configuration. The seal element may then beinitially activated from the first configuration to the second,expanded, configuration. In the second configuration, pressurised fluidfrom the annulus between the apparatus and the bore wall (the annulusfluid) may be utilised to provide a second stage activation in which theseal element is urged into sealing or enhanced sealing engagement withthe bore wall. In particular, but not exclusively, the annulus fluidused to urge the seal element from the second configuration to the thirdconfiguration may comprise fluid from upstream of the restrictioncreated by the seal element defining the second configuration.

Beneficially, embodiments of the present invention provide for aninitial activation of the seal element and a second activation whichutilises the pressurised fluid in the annulus—which may otherwise causeextrusion of the seal element, reduce seal performance, make activationmore difficult or risk failure of the seal—to maintain or enhance theseal with the bore wall. Moreover, by utilising the pressurised fluidpresent in the annulus the use of applied activation forces—which mayotherwise damage the surrounding bore wall or tubulars and increase thesize and weight of the apparatus—may be obviated or reduced.

The seal element may be of any suitable form or construction.

In particular embodiments, the seal element may comprise an annular sealelement and the seal element may be disposed around the mandrel.However, other suitable forms may be used where appropriate. Forexample, the apparatus may comprise a plurality of seal elementsextending around the mandrel, the plurality of seal elements forming theseal between the mandrel and the bore wall.

The seal element may be configured to expand in the presence of aselected activation medium. The activation medium may comprise a fluid.In particular embodiments, the fluid may comprise fluid from the annulusbetween the apparatus and the bore wall.

In particular embodiments, the seal element may comprise a materialwhich swells in response to oil. For example, the seal element maycomprise an oil-swellable material, such as an oil-swellable elastomer.

In other embodiments, the seal element may comprise a material whichswells in response to water. For example, the seal element may comprisea water-swellable material, such as a water-swellable elastomer.

In use, the apparatus may be run into the bore, exposure of the sealelement to the selected activation medium in the annulus fluid causingthe seal element to expand from the first configuration to the second,expanded, configuration to provide the initial activation of theapparatus.

The apparatus may be configured so that the seal element is moveablerelative to the mandrel. In particular embodiments, the apparatus may beconfigured so that, in the second configuration, the annulus fluid isdirected between the seal element and the mandrel. For example, theapparatus may be configured so that the annulus fluid impinges on aninner circumferential surface of the seal element. Thus, the annulusfluid may be used to urge or push the seal element radially outwardsinto sealing or enhanced sealing engagement with the bore wall.

The apparatus may be configured to define a fluid-receiving chamberbetween the seal element and the mandrel. The fluid-receiving chambermay be present when the seal element is in the first, retracted,configuration. Alternatively, and in preferred embodiments, thefluid-receiving chamber may be formed when the seal element expands ormoves from the first configuration to the second configuration.Beneficially, this allows the seal element to define a smaller diameterfirst configuration than would otherwise be possible where afluid-receiving chamber is present during run-in. This may assist inpreventing damage to the seal element during run-in, for example.

Any suitable means for permitting the pressurised annulus fluid to passbetween the seal element and the mandrel may be provided. For example,the apparatus may comprise a fluid passage configured to permit thepassage of the pressurised fluid between the seal element and themandrel.

The fluid passage may comprise an axially-extending fluid passage. Inparticular embodiments, the apparatus may comprise a plurality ofaxially-extending passages.

The passage or passages may be of any suitable form. In particularembodiments, the passage or passages may of hemi-cylindrical form. Wherea plurality of passages is provided, the passages may be arrangedcircumferentially

In use, the passage or passages may be arranged to provide at least someof the fluid communication to the fluid-receiving chamber, thepressurised annulus fluid passing through the passage or passages andimpinging on the seal element forcing or assisting in urging the sealelement into sealing or enhanced sealing engagement with the bore wall.

In some embodiments, the apparatus may be configured so that the sealelement engages the bore wall in the second configuration. For example,and in preferred embodiments, the apparatus may be configured so thatthe seal element provides initial sealing engagement with the bore wallin the second configuration. In such embodiments, the seal element maybe maintained in sealing engagement or urged into enhanced sealingengagement with the bore wall in the third configuration. Alternatively,the apparatus may be configured so that the seal element does notsealingly engage the bore wall in the second configuration. In suchembodiments, the seal element may be urged into sealing engagement withthe bore wall in the third configuration.

In other embodiments, the apparatus may be configured so that the sealelement does not engage the bore wall in the second configuration. Insuch embodiments, the seal element may sealingly engage the bore wall inthe third configuration.

The apparatus may comprise at least one further seal member and, inparticular but not exclusively, the further seal member may beconfigured to define a cup seal.

The or each further seal member may be of any suitable form orconstruction.

The or each further seal member may comprise at least one of: anelastomeric seal member; a compression seal member; a packing member; anexpandable member; a swellable member; an oil-swellable member; awater-swellable member; an inflatable member, or any suitable style ofseal member.

The apparatus may comprise a single further seal member. In particularembodiments, the apparatus may comprise a plurality of further sealmembers.

Where the apparatus comprises a plurality of seal members, the sealmembers may be of the same or different construction.

The further seal members may be selected and/or arranged in order toprovide selected properties to the apparatus. For example, one or moreseal member may comprise a material of greater hardness than one or moreother seal member.

Beneficially, the provision of a seal member having greater hardness mayassist in preventing or at least mitigating extrusion of a seal memberand/or the seal element.

In use, the seal element may be used to activate the further sealmember. For example, the further seal member may be at least partiallyactivated by expansion of the seal element from the first configurationto the second configuration. Alternatively, or additionally, the furtherseal member may be at least partially activated when the seal element isurged from the second configuration to the third configuration.

The apparatus may comprise one or more end ring, and in particularembodiments the apparatus comprises two end rings disposed at opposingends of the apparatus. In particular embodiments, the fluid passage maybe formed or otherwise provided in one of the end rings, for examplearound an inner circumferential surface of the end ring.

At least one end ring may comprise a radially-extending bore forreceiving a retainer and, in particular embodiments, each end ring maycomprise a plurality of radially-extending bores, each for receiving aretainer, such as a grub screw, bolt or the like. In use, the retaineror retainers may be used to secure the end ring to the mandrel.

The apparatus may be configured so that part of the annulus fluid alsoacts towards retaining the seal element and/or one or more seal memberon the mandrel. For example, a component of the force generated by theannulus fluid may be directed radially inwards and so may assist inmaintaining a seal element or seal member on the mandrel.

In use, embodiments of the present invention may utilise fluid pressureboth to urge the sealing element into sealing or enhanced sealingengagement with the bore wall and also to retain the sealing element onthe mandrel. The apparatus may be configured so that the fluid pressureimpinges on selected areas, the selected areas configured to provide therequired forces to urge the seal element radially outwards to providesealing or enhanced sealing engagement with the bore wall and radiallyinwards to assist in maintaining the seal element on the mandrel.

The apparatus may comprise a back-up assembly for supporting the sealelement in maintaining sealing engagement with the bore wall. Theback-up assembly may comprise at least one of: a ring member; a supportmember arranged to extend over at least an end of the seal element; anda collar having a seal-engaging surface arranged to engage the end ofthe seal element, the collar interposed between the end of the sealelement and the support member.

The apparatus may comprise a downhole packer.

The apparatus may comprise a uni-directional downhole packer. Forexample, the apparatus may be configured to be activated by the annulusfluid or differential fluid pressure acting in a selected direction.

The apparatus may comprise a uni-directional cup seal packer.

According to a further aspect of the present invention, there isprovided a method comprising:

providing an apparatus comprising a mandrel and a seal element forestablishing a seal in an annulus between the mandrel and a wall of abore;

disposing the apparatus in the bore,

initially activating the seal element from a first configuration to asecond, expanded, configuration; and

urging the seal element from the second configuration to a thirdconfiguration using fluid from the annulus between the mandrel and thewall of the bore, the seal element in the third configuration providingsealing or enhanced sealing engagement with the bore wall.

It should be understood that the features defined above in accordancewith any aspect of the present invention or below in relation to anyspecific embodiment of the invention may be utilised, either alone or incombination, with any other defined feature, in any other aspect orembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described,by way of example only, with reference to the accompanying drawings, inwhich:

FIG. 1 is an end view of an end view a sealing apparatus according to anembodiment of the present invention; and

FIG. 2 is a longitudinal section view of section A-A of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

The figures show an end view and a longitudinal section view of asealing apparatus 10 according to an embodiment of the presentinvention, the apparatus 10 in the illustrated embodiment comprises adownhole cup seal packer for use in sealing an open or uncased hole. Inuse, the apparatus 10 establishes a seal in an annulus 12 between theapparatus 10 and a wall (shown diagrammatically at 14) of a bore (showndiagrammatically at 16) which prevents passage of fluid along theannulus 12 in a selected direction, for example preventing passage offluid in an uphole direction or in a downhole direction.

The apparatus 10 comprises a mandrel 18 which forms part of a tubingstring such as production conduit or the like (not shown). An annularseal element 20 is disposed around the mandrel 18, the seal element 20comprising a swellable seal element which swells in response to aselected activation fluid in the annulus 12. In the illustratedembodiment, the seal element 20 is constructed from an oil-swellableelastomer and, in use, the seal element 20 may be run into the bore 18in a first, retracted, configuration before being initially activatedfrom the first configuration to a second, expanded, configuration whenexposed to oil in the annulus 12.

The seal element 20 is disposed around the mandrel and is free to moverelative to the mandrel 18 such that, in use, when the seal element 20moves to the second configuration a fluid-receiving chamber C is definedbetween the seal element 20 and the mandrel 18. The annulus fluid may bedirected to the chamber C formed between the seal element 20 and themandrel 18, the pressurised annulus fluid impinging on the innercircumferential surface of the seal element 20 being used to urge orpush the seal element 20 radially outwards into sealing or enhancedsealing engagement with the bore wall 14 and so provide a secondaryactivation of the seal element 20.

As shown most clearly in FIG. 2, annular end rings or gauge rings 22, 24are provided at respective ends of the apparatus 10. The gauge rings 22,24 have radially extending holes defining bores 26 for receiving grubscrews (not shown). The bores 26 are provided in an annular portion 28of the gauge rings 22, 24 which also have a tapered portion 30 at theirdistal ends.

In use, the seal element 20 and the ring 22 are arranged to permit thepassage of the annulus fluid into the fluid-receiving chamber C.

In the illustrated embodiment, the gauge ring 22 also comprises axialpassages or grooves 32 and, in use, the grooves 32 permit additionalfluid communication with the fluid-receiving chamber C.

In the illustrated embodiment, the gauge ring 22 comprises eight grooves32. However, it will be recognised that one groove 32 or a plurality ofgrooves 32 may be provided, as appropriate. Following initial activationof the apparatus 10, annulus fluid may be directed through the grooves32 and into the chamber C, thereby providing an additional activationforce which urges the seal element 20 into sealing engagement (where theseal element 20 is not already in sealing engagement with the bore wall14 in the second configuration) or enhanced sealing engagement (wherethe seal element is already in sealing engagement with the bore wall 14in the second configuration). While the illustrated embodiment providesfor passage of fluid between the ring 22 and the chamber C and throughthe grooves 32, it will be recognised that fluid may be directed to thechamber C by one or both of these.

Referring now to FIG. 2 in particular, the apparatus 10 furthercomprises two further seal members, a first seal member 34 and a secondseal member 36. The seal members 34, 36 are formed separately and bondedor moulded together and, in use, define the cup seal. The first sealmember 34 is beneficially constructed from a material selected with highcompliance to provide good sealing properties with the bore wall 14. Thesecond seal member 36 beneficially is constructed from a material ofgreater hardness than the first seal member 34 and, in use, provides ananti-extrusion effect, preventing or mitigating extrusion of the sealelement 20 and/or the seal members 34, 36.

In use, the seal element 20 is used to at least partially activate thefurther seal members 34, 36 by urging or pushing the seal membersradially outwards to define the cup seal.

Beneficially, embodiments of the present invention provide for aninitial activation of the seal element and a second activation whichutilises the pressurised fluid in the annulus—which may otherwise causeextrusion of the seal element, reduce seal performance, make activationmore difficult or risk failure of the seal—to maintain or enhance theseal with the bore wall. Moreover, by utilising the pressurised fluidpresent in the annulus the use of applied activation forces—which mayotherwise damage the surrounding bore wall or tubulars and increase thesize and weight of the apparatus—may be obviated or reduced.

It should be understood that the embodiment described herein is merelyexemplary and that various modifications may be made thereto withoutdeparting from the scope of the invention.

For example, the apparatus may further comprise a back-up assembly 38for supporting the seal members 34, 36 in maintaining sealing engagementwith the bore wall 14.

While the illustrated embodiment describes apparatus for use in openhole, the apparatus may alternatively be used in a cased hole. While theseal element and seal members are described above at separatecomponents, one or more of these may comprise a unitary component.

The apparatus may alternatively or additionally be configured so thatthe annulus fluid impinges on an end face of the seal element. In suchembodiments, at least one of the seal element, the mandrel or othercomponents of the apparatus may be formed or arranged to urge the sealelement radially outwards in response to an axial force generated by theannulus fluid impinging on the end of the seal element. For example, atleast one of the mandrel, seal element, first seal member may betapered.

While in the illustrated embodiment, the initial activation may be takenup by expansion of the seal element, the apparatus may alternatively oradditionally be configured to receive an initial applied activationforce. The applied initial activation force may comprise an axial force,such as an axial compressive force. The apparatus may further comprisean activation arrangement for applying the initial activation force tothe seal element. The activation arrangement may be of any suitable formor construction, and may comprise a setting tool or the like. Theactivation arrangement may form part of the apparatus. Alternatively,the activation arrangement may be provided separately from theapparatus.

1. A sealing apparatus for use in establishing a seal in an annulus between a mandrel and a bore wall, the apparatus comprising: a mandrel; and a seal element disposed on the mandrel, the seal element configured to define a first configuration and a second, expanded, configuration, the apparatus configured so that in the second configuration fluid from the annulus acts on the seal element to urge the seal element from the second configuration to a third configuration providing sealing or enhanced sealing engagement with the bore wall.
 2. The apparatus of claim 1, wherein the first configuration comprises a retracted configuration.
 3. The apparatus of claim 1, wherein at least one of: the seal element comprises an annular seal element; the seal element is disposed around the mandrel; the apparatus comprises a plurality of the seal elements extending around the mandrel.
 4. (canceled)
 5. (canceled)
 6. The apparatus of claim 1, wherein the seal element is configured to expand in the presence of a selected activation medium.
 7. The apparatus of claim 6, wherein at least one of: the activation medium comprises a fluid; the fluid comprises fluid from the annulus between the apparatus and the bore wall;
 8. (canceled)
 9. The apparatus of claim 6, wherein at least one of: the seal element comprises a material which swells in response to oil; the seal element comprises an oil-swellable material, such as an oil-swellable elastomer; the seal element comprises a material which swells in response to water the seal element comprises a water-swellable elastomer.
 10. (canceled)
 11. (canceled)
 12. (canceled)
 13. The apparatus of claim 1, wherein the apparatus is configured so that the seal element is moveable relative to the mandrel.
 14. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that, in the second configuration, the annulus fluid is directed between the seal element and the mandrel; the apparatus is configured so that the annulus fluid impinges on an inner circumferential surface of the seal element.
 15. (canceled)
 16. The apparatus of claim 1, wherein at least one of: the apparatus is configured to define a fluid-receiving chamber between the seal element and the mandrel; the fluid-receiving chamber is present when the seal element is in the first configuration; the fluid-receiving chamber is formed when the seal element expands or moves from the first configuration to the second configuration.
 17. (canceled)
 18. (canceled)
 19. The apparatus of claim 1, wherein at least one of: the apparatus comprises a fluid passage configured to permit the passage of the pressurised fluid between the seal element and the mandrel; the fluid passage comprises an axially-extending fluid passage:, the apparatus comprises a plurality of the fluid passages the fluid passage or passages are of hemi-cylindrical form: the passages are arranged circumferentially.
 20. (canceled)
 21. (canceled)
 22. (canceled)
 23. (canceled)
 24. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that the seal element engages the bore wall in the second configuration; the apparatus is configured so that the seal element provides initial sealing engagement with the bore wall in the second configuration; the apparatus is configured so that the seal element is maintained in sealing engagement or urged into enhanced sealing engagement with the bore wall in the third configuration; the apparatus is urged into sealing engagement with the bore wall in the third configuration.
 25. (canceled)
 26. (canceled)
 27. (canceled)
 28. The apparatus of claim 1, wherein at least one of: the apparatus comprises at least one further seal member; the further seal member is configured to define a cup seal; the or each further seal member comprises at least one of: an elastomeric seal member; a compression seal member; a packing member; an expandable member; a swellable member; an oil-swellable member; a water-swellable member; an inflatable member, or any suitable style of seal member;
 29. (canceled)
 30. (canceled)
 31. The apparatus of claim 28, wherein the apparatus comprises a single further seal member.
 32. The apparatus of claim 28, wherein at least one of: the apparatus comprises a plurality of further seal members; the further seal members are of the same construction; the further seal members are of different construction; the further seal members are selected and/or arranged in order to provide selected properties to the apparatus; one or more further seal member may comprise a material of greater hardness than one or more other seal member.
 33. (canceled)
 34. (canceled)
 35. (canceled)
 36. (canceled)
 37. The apparatus of claim 28, wherein at least one of: the apparatus is configured so that the seal element activates the further seal member; the apparatus is configured so that the further seal member is at least partially activated by expansion of the seal element from the first configuration to the second configuration; the apparatus is configured so that the further seal member is at least partially activated when the seal element is urged from the second configuration to the third configuration.
 38. (canceled)
 39. (canceled)
 40. The apparatus of claim 1, wherein at least one of: the apparatus comprises one or more end ring; the apparatus comprises two end rings disposed at opposing ends of the apparatus; the apparatus comprises one or more end ring and a fluid passage is formed in one of the end rings and configured to permit the passage of the pressurised fluid between the seal element and the mandrel; the apparatus comprises one or more end ring and at least one end ring comprises a radially-extending bore for receiving a retainer; the apparatus comprises one or more end ring and each end ring comprises a plurality of radially-extending bores, each for receiving a retainer.
 41. (canceled)
 42. (canceled)
 43. (canceled)
 44. (canceled)
 45. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that part of the annulus fluid acts towards retaining the seal element on the mandrel; the apparatus comprises at least one further seal member and is configured so that part of the annulus fluid acts towards retaining one or more further seal member on the mandrel.
 46. (canceled)
 47. The apparatus of claim 1, wherein the apparatus comprises a back-up assembly for supporting the seal element in maintaining sealing engagement with the bore wall.
 48. The apparatus of claim 1, wherein at least one of: the apparatus comprises a downhole packer; the apparatus comprises a uni-directional downhole packer; the apparatus comprises a cup seal packer.
 49. (canceled)
 50. (canceled)
 51. A method comprising: providing an apparatus comprising a mandrel and a seal element for establishing a seal in an annulus between the mandrel and a wall of a bore; disposing the apparatus in the bore, initially activating the seal element from a first configuration to a second, expanded, configuration; and urging the seal element from the second configuration to a third configuration using fluid from the annulus between the mandrel and the wall of the bore, the seal element in the third configuration providing sealing or enhanced sealing engagement with the bore wall.
 52. (canceled)
 53. (canceled) 